are stuff like "x sign's birthsone, x sign's birthflower" a thing??? do signs rule certain plants and stones? cause everytime i look it up it shows up a different thing lmao
I don't understand the first question at all. As for the second, "rulership" is not really what it is, because in astrology that means something else. It's about the principle of similitude or correspondence in either Hermetism, Alchemy and Renaissance/Medieval science. Although, as far as I can remember, I've never seen zodiac signs being assigned stones and plants correspondences, just the planets. But I wouldn't doubt there's something like that and I also wouldn't be against it.
Disclaimer: Between Hermes Trismegistus, Vettius Valens, Agrippa and William Lilly there's an incredible amount of centuries, so they are not all the same and no one living in the same time thinks about things in the same way, much less these figures who are separated by so much time and space, even if there's a chain of influence between them, so it is important not to generalize their philosophies.
You see correspondences greatly used and explained by Alchemists in occult books like the Renaissance Cornelius Agrippa's first of the "Three Books of Occult Philosophy". And in strictly astrological works, everyone usually puts a list of correspondences, of planets with plants, stones, people, professions, places, diseases, natural phenomena etc. The zodiac signs' correspondences are usually with parts of the body, types of illnesses, places…
In the Emerald Tablet it's said that "what is above is like what is below, and what is below, like that which is above to do the miracle of one only thing", which I'm lucky enough to be brazilian and have Jorge Ben Jor to make me memorize it. This is interpreted in many ways, but for astrologers this is mostly important because it's about the correspondences of the stars to the things on earth. You were born as sign x was rising on the horizon. There's similitude between you and that sign because you emulate one another in your action of being born at the same time. That's the aemulatio form of similitude. I recommend reading Les Mots et les Choses: Une archéologie des sciences humaines by Michel Foucault (criminally translated to english as "The Order of Things: An Archaeology of the Human Sciences"), on the second chapter "The Prose of the World" where he talks about the 4 similitudes. It's obviously not an occult book, it's a very important book for other reasons, but he does a pretty good job at explaining scientific thought before the Enlightment movement, which helps those learning about astrology.
Correspondence is all that astrology does. Venus is like love, war is like Mars, belief is like Jupiter, doubt is like Mercury etc. "And as all things have been and arose from one by the mediation of one: so all things have their birth from this one thing by adaptation. The Sun is its father, the moon its mother, the wind hath carried it in its belly, the earth is its nurse."
In horary astrology, the correspondences of the signs help answering questions. If you lost an object, for example, the second house ruler in a fire or air sign can mean that you'll find the object in a high place, because fire and air are the lightest elements and they go up; but if it's in Taurus it could be on the ground in a garden, or a pasture; if it's in Leo it could be near a fire place, etc. Check out William Lilly's "Christian Astrology" to learn about horary and these correspondences.
Any magical practice will use a kind of correspondence to make offerings to gods, daimons, spirits. Correspondences with plants or stones are important in magical practices using astrology, because in theory, by using a specific plant, stone, incense, etc. associated with planet x, you will be invoking the spirits of that planet, that is, if you believe planets are/have spirits. I think that's Agrippa's understanding, for example. I recommend reading his book 1, don't count on me to be reliable on that. Others will say that you don't invoke the said spirits of the planets, but it's about creating a chain of correspondences and the spirits connected to those correspondences will be invoked. But I can't say much, I don't know enough about magic. The most notable source on astrological magic today is Christopher Warnock.
















